function out = fcn(u1,u2)
coder.extrinsic('ismember');
out = zeros(size(A, 1),1);
[~, out] = ismember(A,[u1 u2],'rows');
This version assumes that multiple rows might match, and assumes that you were looking for the index of the match, not a vector of logical true the length of the number of matches, empty for no match. If there is always definitely exactly one match then initialize out to 0.
If one match is what is expected then you should rewrite your code to avoid ismember since code cannot be generated for ismember.
Result = logical(size(A, 1),1);
Result = A(:, 1)==u1 & A(:, 2)==u2;
And then that convert that into the desired output, such as
out = 0;
out = find(Result, 1);
